Pancreatic cancer (PC) is a disease of insidious progression and high lethality, with the majority of tumors having extended beyond the confines of the pancreas at the time of diagnosis. The early diagnosis of PC remains a challenging endeavor that will require multidisciplinary approaches, including imaging studies, tissue sampling, and analysis of body fluids from patients. There is no specific tumor marker available for diagnosing pancreatic cancer. The principal reason for this grim prognosis is our inability to diagnose the disease at an early, localized, and potentially curable stage. In an extensive study on the expression analysis of various mucin (MUC) genes, we demonstrated specific and differential expression of MUC4 in pancreatic adenocarcinomas as compared to the normal pancreas or chronic pancreatitis tissues. The central hypothesis of this proposal is that the MUC4 is detected in peripheral blood mononuclear cells (PBMCs) and fine needle aspirates (FNAs) of pancreatic cancer patients but not of healthy individuals or those with non- neoplastic pancreatic diseases. Three specific aims are proposed. . Aim I will compare the expression of MUC4 by real-time RT-PCR in PBMCs of patients with pancreatic cancer, pre-malignant pancreatic diseases, pancreatitis and aged-matched healthy subjects. This aim will establish the sensitivity, specificity, accuracy and diagnostic potential of MUC4 mRNA in PBMCs. Additionally, it will determine whether the detection of MUC4 mRNA in blood correlates with tumor stage, tumor progression, recurrence or response to therapy. Aim II will identify the cell types in PBMCs that are positive for MUC4. A subset of patient's PBMCs will be FACS-analyzed to investigate the nature of the cell type(s) that express MUC4 mRNA. We will investigate the possibilities that MUC4 in PBMCs is from: i) circulating pancreatic tumor cells;ii) circulating dendritic cells or macrophages that have acquired MUC4 mRNA through phagocytosis or pinocytosis of primary or metastatic tumor cells;or iii) PBMCs that have turned on the expression of MUC4. Aim III will investigate the expression of MUC4 and nanostructural cytological changes in fine needle aspirates (FNAs) from PC patients and attempt to distinguish them from chronic pancreatitis and other benign diseases using immunocytochemical and partial wave spectroscopic (PWS) analyses. MUC4 protein will be measured in FNAs and will be correlated with the sensitivity and specificity of diagnosis. In addition, partial wave spectroscopy (PWS) will be utilized to improve the ability of cytological examination on FNAs to distinguish PC cells from non-neoplastic cells. Associating PWS signatures with MUC4 expression will further assist in disease classification and planning/formulating management strategies. Taken together, these aims will establish the utility of MUC4 in the diagnosis of lethal pancreatic cancer. PUBLIC HEALTH RELEVANCE: The overall goal of this study is to develop a novel molecular diagnostic test(s) for lethal pancreatic cancer. We will investigate the diagnostic utility of MUC4 detection in peripheral blood mononuclear cells and fine needle aspirates of pancreatic cancer patients with high sensitivity and specificity. The proposed investigations are expected to improve the current diagnosis of pancreatic cancer and can easily be translated to clinics after successful multi-center evaluation.